There are several well known methods of and apparatus making twisted electrical cable products. For example, U.S. Pat. Nos. 3,686,843; 4,133,167; 4,171,609; 4,215,529; 4,426,837; 5,239,813; and 5,557,914 disclose a few of the many different types of twisting and cabling methods and apparatus which are used for twisting conductors or wires and for making twisted electrical cables. In another conventional method, a plurality of aluminum or copper wires is stranded together into a single bare stranded conductor which is then insulated with a polymeric insulation, preferably by extrusion. The insulated stranded conductor is wound onto a reel, tested on its reel which is then stored for later use. Two or more of the reels of insulated stranded conductor are taken from storage and mounted in a cabling apparatus for simultaneous pay out. As the conductors are payed out from the reels, they are twisted together to form a twisted cable and the twisted cable is taken up on a reel. Typically, each insulated conductor is payed off its reel in an untwisted condition, and the conductors are then twisted together in a planetary assembly, i.e., without each individual conductor being twisted about its own longitudinal axis.
The aforementioned conventional method has been used heretofore to manufacture secondary electrical distribution cable, such as, for example, 600 volt triplex UD cable, and represents the state-of-the-art for manufacture of such cable. One disadvantage of the conventional method is large number of manufacturing steps involved in the manufacture of the cable. The number of manufacturing steps is increased in part because of the requirement to provide in-process handling and inventory control of the large reels of uninsulated bare stranded conductors, which typically comprise 7, 19 or 37 individual copper or aluminum wires, as well as in-process handling and inventory control for the same large reels after the insulation material has been extruded onto the uninsulated bare stranded conductors and cured to form the insulated conductors that are subsequently cabled together into the twisted electrical distribution cable. Substantial in-process storage space is also required for both the large reels of bare stranded conductors, as well as for the equally large reels of insulated stranded conductors. In addition, each extrusion line for applying the plastic insulation to the stranded conductors requires substantial plant floor space for the equipment necessary to unreel the bare stranded conductor, extrude the insulation onto the stranded conductor, and take-up the insulated stranded conductor on a reel. Substantial floor space is especially required for the cooling troughs necessary to cool the insulation material before the insulated stranded conductor is taken up onto a reel.
It would be desirable, therefore, to provide a method and an apparatus that reduces the in-process handling steps, the in-process storage and plant floor space requirements necessary for the conventional method and apparatus for making twisted electrical cable, such as 600 volt UD cable.